Use of the Actinobacillus actinomycetemcomitans leukotoxin promoter to drive expression of the green fluorescent protein in an oral pathogen

The gene for the green fluorescent protein, gfp, was cloned, under the control of the Actinobacillus actinomycetemcomitans leukotoxin (ltx) promoter, in the A. actinomycetemcomitans shuttle vector, pSU20. A. actinomycetemcomitans containing the ltx‐gfp construct emitted bright green fluorescence in the standard invasion assay using epifluorescence microscopy. These data demonstrate that the green fluorescent protein will be a useful tool for the live analysis of A. actinomycetemcomitans interactions with host cells, and that the ltx promoter can be used to drive the expression of non–A. actinomycetemcomitans genes.